From what I recall, all race refers to is the difference in allele frequency between populations. There is no universal gene carried by each race that we can point to as a signifier of that race. Instead, a pattern emerges when you consider these populations in aggregate, in which some alleles are found in up to 90% of the population but others are a bit less so. Typically, the genetic difference between the two most genetically distinct individuals in the population is going to be greater than the average genetic difference between the two populations, otherwise known as "races". The only alleles that are unique to said populations (discounting them being spread by relatively recent interracial pairings) are only found in a minority of the population, the classic example being that allele that controls for sickle cell anemia and supposedly bestows some sort of resistance to malaria.
The races could represent a step in the creation of new species, but as those of us that have studied Hardy-Weinberg equilibrium can attest, gene flow between populations is a sign that no evolution is occurring, especially given the small amount of time that has passed since our species has left Africa. We've even found that apparently there was more gene flow back into Africa than previously thought and, accordingly, more sub-Saharan Africans carrying alleles of Neanderthal origin.